Ingot moulds

ABSTRACT

A plurality of elements are adhered together via a layer of heat-vulcanisable rubber of specified properties. This method may be used to fix ingot mould hot top lining slabs to the walls of an ingot mould or head box.

United States Patent Clark et al. 1 July 1, 1975 1 INGOT MOULDS [75]Inventors: Peter Stanley Clark; David John References Cited Bloodworth,both of Nechells, UNTTED STATES PATENTS Brmmgham England 3,258,3896/1966 061611166 615 211 156/338 x 73 Assignee; Foseco InternationalLimited, 3,681,190 8/1972 Dahlquist 156/338 X Birmingham England3,749,628 7/1973 Nancarrow et all 249/106 3,751,331 8/1973 Leverkusen156/338 X [22] Filed: Mar. 23, 1973 211 App} N 344 0 4 PrimaryExaminerEdward G. Whitby Attorney, Agent, or FirmCushman, Darby &Cushman [30] Foreign Application Priority Data Mar. 23, 1972 UnitedKingdom 13702/72 Apr. 20, 1972 United Kingdom 18345/72 [57] ABSTRACT Aplurality of elements are adhered together via a [52] US. Cl. 156/71;156/338; 164/137; layer of heat-vulcanisable rubber of specified proper-249/106; 260/237 H; 260/942 R; 428/465 ties. This method may be used tofix ingot mould hot [51] Int. Cl. B22D 7/10 top lining slabs to thewalls of an ingot mould or head [58] Field of Search 156/71, 338;161/217, 221; box.

16 Claims, 1 Drawing Figure INGOT MOULDS This invention relates to amethod of adhering a plurality of like or dissimilar elements; inparticular this invention relates to fixing ingot mould hot top liningslabs to the walls of an ingot mould or head box.

For reasons of manufacturing simplicity. ingot mould hot top liningslabs are usually made flat and in use forced to fit the flat or moreusually cambered and tapered walls of the ingot mould head or head boxit is desired to line. Most types of hot top lining slabs, however,possess a degree of resilience which tends to spring the slab away fromthe wall of the mould or head box unless it is very firmly affixedthereto. Even fairly flexible materials are difficult to attach to thegenerally fairly uneven mould or head box wall.

One method of fixing hot top slabs in the desired position is bymechanically nailing or clipping the slabs in place. This method isinconvenient, time-consuming, expensive and prone to failure. Numerousprevious attempts to adhere insulators to mould walls have beenunsatisfactory, since no single adhesive was found which would operatesatisfactorily over the wide temperature range required (roomtemperature to 300C) and at the same time fully support the insulatoragainst the camber and usual unevenness of cast iron ingot mould walls.

The objection of the present invention is to overcome theabove-mentioned difficulties by means of an adhesive system comprising aheat-vulvanisable rubber.

According to the present invention, there is provided a method ofadhering a plurality of like or dissimilar elements, which comprisesadhering the elements together via a layer of a heatvulcanisable rubberhaving the following properties:

a. a Mooney viscosity. after 4 minutes at 100C of 24 70 units b. atorque after 1 minute at 160C of l-3O inch.lbs.

c. a scorch time of not greater than 3 /2 minutes d. a vulcanisationrate of 9-20 inch.lbs. per minute e. a time to 100% cure of 10-30minutes, and

f. a quality level of 50-90 inch.lbs.

Property (a) was measured using a Mooney viscometer and properties (b)to (f) using a Monsanto Rheometer type LSD fitted with micro dies.

It is observed that other rubber compositions which have propertieswhich do not fulfil all the above conditions are of little value inadhering ingot mould hot topping slabs since they tend to adhere theslabs insufficiently well, especially to hot and cambered or uneveningot moulds or head boxes. The method of the present invention is ofparticular value in adhering flexible deformable not very resilient hottop lining slabs, but can be used with the more rigid types.

The rubber may be present between the slab and the mould or head boxsurface in the form ofa plurality of strips of material extending acrossthe slab or a thick rubbery mass, eg a single sheet of rubber materialmay cover the whole area of the slab.

Thus, for example, tapes of unvulcanised rubber of width 6-50 mm andthickness 0.7 1.5 mm. preferably about 1mm may be used.

Alternatively, sheets of calendered rubber 100-600 mm wide and 0.25 2.0mm (preferably 0.36 0.5 mm) thick may be used.

The total area of slab covered by the rubber tape or sheet material mayvary from 10-1007: and is preferably 15-40%. Similarly the sheet may bemade up from a plurality of tapes.

The preferred method of attachment of the rubber tape or sheet to thehot top lining slabis first to prime the surface of the slab with asuitable primer. and then apply the tape or sheet while the primer isstill wet. Preferred primers for use in this connection are solutions ordispersions of rubber. most preferably a rubber similar in constitutionto that of the tapes or sheet. It is possible in some cases to adherethe rubber tape or sheet by "autohesion after the primer has dried. butthis is sometimes rendered ineffective by the presence of sulphur bloomon the tape or sheet. Application while the primer is still wetovercomes this difficulty.

The adhesion of the rubber tape or strip to the mould or head box wallis preferably by means of a tacky pressure-sensitive adhesive material.Polymers of 2- ethylhexyl acrylate which are available commercially asadhesive materials are the adhesives of choice for this purpose, thoughother poly (acrylic ester) materials may also be used.

In order to promote adhesion between the lining slab and the rubber tapeor sheet. the surface of the lining slab may be contoured appropriately.e.g.. by dimpling, e.g., depressions spiked into the slab surface whichincrease the area of contact of the primer solution. Furthermore, thesurface of the slab may advantageously be relieved by grooves. These aidthe escape of gases generated in the slab and in its fixing systemduring casting. Likewise, the surface of the rubber sheet or tapematerial may be flat or corrugated or otherwise textured, e.g., byembossing. Any known surface treatment process for effecting these maybe used.

The adhesive and rubber sheet or tape material used should possesssufficient bonding and tensile strength to hold the slab in place attemperatures up to 300C, and this strength should be developed onapplication of the slab to the ingot mould or head box wall.

It is found that the temperature rangeof the substrate over which therubber sheet or tape material will adhere may vary with the type ofrubber used, and in such cases, in order to provide ingot hot top slabswhich are attachable to mould surfaces at very widely differingtemperatures, it may in some cases be desirable to provide rubber sheetor tape material of more than one type on the slab surface; for example,alternate tapes of synthetic and natural rubber, each having the properrties noted above may be used.

Suitable rubber stocks for use in the present invention include naturalrubber, butyl and nitrile rubbers and neoprene rubber. Of these types,nitrile rubbers are not preferred since the temperatures undergone byingot mould hot top slabs in use may decompose the rubber and give riseto noxious fume. The rubber sheet or tape material may be a solid rubberor it may be of blown, expanded or foamed rubbery material. The rubbersheet or tape material is preferably formed of a rubber compositionincluding customary fillers, extenders and the like to produce asatisfactory product.

In practice, the most convenient way of putting the invention intoeffect is to extrude a strip of wet primer onto the rear surface of aslab, (i.e., the non-moltenmetal contacting surface), adhering asuitable length of rubber tape to the wet primed slab, and thensubsequently pressing the slab onto the ingot mould or head box wall viaan intermediate layer of adhesive. In this respect a plurality ofstripes of wet primer may be laid 3 down followed by a correspondingnumber of rubber tapes.

The lengths of tape may be coated with a layer of adhesive on one sideand for the purposes of ease of stor agethe thus coated rubber tapes maybe coiled up with an interleaved release paper strip. Alternatively.unco'ated rubber tapes may be applied to the wet primed slab and theadhesive applied either before the slabs are despatched or immediatelyprior to the slabs being at tached to the desired site.

,It is naturally, preferable in such a case to ensure that the tapeshave a sufficient storage life after manufacture. Anti-oxidants andother additives may be included to ensure this. Commercially, for use inlining ingot mould heads and head boxes, a shelf life of 3 months isdesirable, both as stored tape and when applied to a hot topping slab.

.In an alternate method, the tapes are not preformed as such and thenattached to the surface; they may be extruded onto a primed or unprimedsurface in the form of a strip of extruded composition whichsubsequently cures (e.g. by heat or solvent evaporation) to give arubber tape compound firmly adhered to the sur face.

Most preferably, the primer comprises, in solution in a suitablesolvent, a rubber composition of the type defined above for the tapes,and a tackifying agent. The preferred solvents are chlorinatedhydrocarbon solvents, e.g., dichloromethane, dichloroethane, trichlo-,roethylene, 1,1 ,l-trichloroethane, tetrachloroethylene.

Mixtures of such solvents may be used, in order to adjust, if required,solvent evaporation rate and/or the depth of penetration of the primerthrough the backing surface of the tile.

The primer solution preferably comprises -40% total solids, dependingupon the viscosity required. The preferred method of applying the primeris flow under gravity through a die plate. However, the primers may beof thin sprayable consistency, medium brushing consistency, or of thickconsistency for application by ex trusion by suitable means, e.g., anextrusion head, a squeeze bottle or a grease-gun" type of applicator.

The viscosity of the primer solution may be varied by changing the totalsolids content, and the evaporation rate may be varied by using any ofthe different solvents mentioned above either singly or in admixture.

The tackifying agent is preferably a coumaroneindene resin. The weightratio of rubbery material to tackifying agent in the primer ispreferably from l:l to 10:1, the former giving a very highly tackyprimer film.

The primers may be made up by merely mixing the ingredients together,e.g., in a Z-blade mixer. The

primer may then be applied to the slab backing in strips correspondingto the disposition of the rubber strips to be subsequently applied.

The primer is applied to the backing at suitable application rate e.g.,50-150 gms/ft of area of surface primed, and the unvulcanised rubbertape, coated on one side only with the previously mentioned pressuresensitive adhesive, is then applied to the wet rubber primed surfaceofthe slab, uncoated (pressure sensitive adhesive-free) side toward theprimed surface. This is best done by rolling the tape with pressure onto the primed surface, the uppermost surface (adhesive coated side)being protected with siliconised release paper.

The assembly is now allowed to dry and it is found that a very strongbond has formed between the dried primer film of tackified rubber andthe unvulcanised rubber tape, so that primer and rubber tape formvirtually an integral material, and that the primer is adheredtenaciously to the slab. So adhered, the rubber tape and slab are verysecurely adherent to each other. being resistant to high shear forces inplane parallel to that of the slab, and high transverse tensile forcesin directions perpendicular thereto, over a temperature range of 0. to300C.

Typical examples of suitable primer compositions are:

20 parts by weight 880 parts by weight Coumarone-indcnc liquid resinDichloromethane This formulation is of low viscosity suitable for sprayapplication.

3. Natural unvulcanised rubber compound (tape material) Coumaronc-indeneresin Dichloromethane 200 parts by weight 40 parts by weight 880 partsby weight This formulation is a higher viscosity formula. This issuitable for hand extrusion through a flexible aluminium or polythenetube or bottle, or extrusion by mechanical means.

If necessary, for specialised adhesion applications, the unvulcanisedrubber tape compound itself may be tackified by the addition of 5-25parts of coumarone resin per parts of the basic formulation. Thistackification of the tape itself increases the adhesion of the tape onto the primed surface.

It is also observed that the heat vulcanisable rubber materials, forexample tapes and sheets, used in the method of the present inventionmay also be employed for a variety of other purposes for fixing togethertwo like or dissimilar materials. Such adhesion may be accomplished attemperatures from below OC to 400C.

The accompanying drawing shows, in part cutaway perspective view, a hottop lining slab according to the present invention adhered in position.

Referring to the drawing, a lining slab 1 has a plurality of grooves 2in its back and is also dimpled as at 3. Across the back of the slabsare strips of dried down primer 4 onto which are adhered tapes of rubber5. These tapes are adhered to the surface of a head box by a thin layerof a polymerised Z-ethyl-hexyl-acrylate adhesive 6.

The following are examples of two suitable formulations for. makingvulcanisable rubber tapes for use in the present invention, Parts aregiven by weight.

EXAMPLE 1 A suitable Neoprene rubber formulation is as follows:

parts Neoprene WRT (ex DuPont) l()() (Polymer) Light magnesium oxide 4(Acid accelerator) SRF Carbon Black 60 (Filler) Dutrex R (ex Shell) 11)(Softening oil) Stearic acid 0.5 (Cure activator) Z-mercapto imidazolinc0.75 (Cure accelerator) Zinc oxide 5 (Curing agent) Properties of thisformulation are as follows:

a) viscosity (4 min. 100C) 50 units b) torque (160C. 1 min) 29 inch.lb.c) scorch time 2% min. d) vulcanisation rate 1 1 inch.lb/min time to100% cure 30 min. f) quality level 85 inch.lb.

EXAMPLE 11 A suitable natural rubber formulation is as follows:

Natural rubber (Ribbed parts smoked sheets grade 1 100 (polymer) Zincoxide (Cure activator) Stearic acid 3 (Cure activator) Carbon black(Cabot carbon) 50 (Filler) Octaminc (a diisobutyleneldiphenyb aminereaction product) 1 (Anti-oxidant) di-2-benzthiazyl disulphide 1 C ureaccelerator) Sulphur 3 (Curing agent) Properties of this formulationwere as follows:

a) Mooney viscosity (4 min, 100C) 25 units b) torque (160C. 1 min) 20inch.lb. c) scorch time 2 mins. d) vulcanising rate 14 inch.lb./min. e)time to 100% cure mins. f) quality level 60 inch.lb.

We claim:

1. A method of adhering a plurality of elements, which comprisesadhering together an insulator in the form of a hot top lining slab toan inner metal surface of an ingot mould or a head box via a layer of aheat-vulcanisable rubber having the following properties:

a. a Mooney viscosity, after 4 minutes at 100C of 24-70 units;

b. a torque after 1 minute at 160C of l30 inch.lbs.;

c. a scorch time of not greater than 3 /2minutes;

d. a vulcanisation rate of 9-20 inch.lbs. per minute;

e. a time to 100% cure of 10-30 minutes, and

f. a quality level of 50-90 inch.lbs. WE CLAIM:

2. A method according to claim 1 wherein a surface of one of theelements is first primed with a solution or dispersion of a rubber andthen heat-vulcanisable rubber is applied to the primed surface while theprimer is still wet.

3. A method according to claim 2 wherein the rubber has substantiallythe constitution of the subsequently applied heat-vulcanisable rubber.

4. A method according to claim 2 wherein the solu tion or dispersioncomprises a tackifying agent.

5. A method according to claim 4 wherein the weight ratio ofrubberztackifyingagent in the solution or dispersion is from 1:1 to10:1. 1

6. A method according to claim 2 wherein the primer is applied at acoating weight from 50 to 150 gm.ft.'

7. A method according to claim 2 wherein the primed element is the hottop lining slab and in which a tacky pressure-sensitive adhesivematerial is utilized to bind the rubber to the inner surface of theingot mould or head box.

8. A method according to claim 7 wherein the adhesive material is apolymer of an acrylic ester.

9. A method according to claim 1 wherein the heat-vulcanisable rubber isutilised as a plurality of strips extending across the surface of one ofthe elements.

10. A method according to claim 9 wherein at least two such strips areof different rubbers, each different rubber having the propertiesdefined in claim 1.

11. A method according to claim 1 wherein the heat-vulcanisable rubberis utilised as a single sheet.

12. A method according to claim 1 wherein the heat-vulcanisable rubbercovers from 15 to 40% of the area of the surface to which it is applied.

13. A method according to claim 1 wherein the heat-vulcanisable rubberis a natural, butyl or neoprene rubber.

14. A method of adhering a hot top lining slab to an inner surface of aningot mould or head box, which method comprises first priming the rearsurface of the lining slab with a solution comprising a rubber and atackifier; then extruding a plurality of strips of a heat-vulcanisablerubber having the following properties:

a. a Mooney viscosity, after 4 minutes at C of 2470 units;

b. a torque after 1 minute at 160C of 1-30 inch.lbs.;

c. a scorch time of not greater than 3 /2 minutes:

(1. a vulcanisation rate of 9-20 inch.lbs. per minute;

e. a time to 100% cure of 10-30 minutes, and

f. a quality level of 5090 inch.lbs. onto the primed surface while theprimer is still wet; a1- lowing the assembly to cure to give a rubberstrip firmly adhered to the surface; and adhering the rubber strip tothe inner surface of the ingot mould or head box with a tacky pressuresensitive material.

15. A hot top lining insulator slab assembly prepared by first primingthe rear surface of the lining slab with a solution comprising a rubberand a tackifier; then extruding a plurality of strips of aheat-vulcanisable rubber having the following properties:

a. a Mooney viscosity, after 4 minutes at 100C of 24-7O units;

a torque after 1 minute at 160C of inch.lbs; a scorch time of notgreater than 3V2minutes;

a vulcanisation rate of 920 inch.lbs. per minute; a time to 100% cure of10-30 minutes, and

a quality level of 50-90 inch.lbs. onto the primed surface while theprimer is still wet: allowing the assembly to cure to give a rubberstrip firmly adhered to the surface.

16. A method of adhering a plurality of elements, which comprisesadhering together an insulator in the form of a hot top lining slab toan inner metal surface of an ingot mould or a head box via a layer of aheat-vulcanisable rubber in the form of a plurality of strips extendingacross the surface of one of the elec. a scorch time of not greater than3 /2 minutes; ments. said rubber having the following properties; d. uvulcanisation rate of 9-20 inch.lbs. per minute;

a. a Mooney viscosity, after 4 minutes at 100C of e. a time to 100% cureof 10-30 minutes. and

24-7O units; f. a quality level of 50-90 inch.lbs.

* l l =l b. a torque after 1 minute at 160C of 1-30 inch.lbs.; 5

1. A METHOD OF ADHERING A PLURAITY OF ELEMENTS, WHICH COMPRISES ADHERINGTOGETHER AN INSULATOR IN THE FORM OF A HOT TOP LINING SLAB TO AN INNERMETAL SURFACE OF AN INGOT MOULD OR A HEAD BOX VIA A LAYER OF AHEAT-VULCANISABLE RUBBER HAVING THE FOLLOWING PROPERTIES: A. A MOONEYVISCOSITY, AFTER 4 MINUTES AT 100*C OF 24-70 UNITS, B. A TORQUE AFTER 1MINUTE AT 160*C OF 1-30 INCH.LBS., C. A SCORCH TIME OF NOT GREATER THAN3 1/2 MINUTES, D. A VULCANISATION RATE OF 9-20 INCH.LBS. PER MINUTE, E.A TIME TO 100% CURE OF 10-30 MINUTES, AND F. A QUALITY LEVEL OF 50-90INCH.LBS. WE CLAIM:
 2. A method according to claim 1 wherein a surfaceof one of the elements is first primed with a solution or dispersion ofa rubber and then heat-vulcanisable rubber is applied to the primedsurface while the primer is still wet.
 3. A method according to claim 2wherein the rubber has substantially the constitution of thesubsequently applied heat-vulcanisable rubber.
 4. A method according toclaim 2 wherein the solution or dispersion comprises a tackifying agent.5. A method according to claim 4 wherein the weight ratio ofrubber:tackifying agent in the solution or dispersion is from 1:1 to10:1.
 6. A method according to claim 2 wherein the primer is applied ata coating weight from 50 to 150 gm.ft.
 2. 7. A method according to claim2 wherein the primed element is the hot top lining slab and in which atacky pressure-sensitive adhesive material is utilized to bind therubber to the inner surface of the ingot mould or head box.
 8. A methodaccording to claim 7 wherein the adhesive material is a polymer of anacrylic ester.
 9. A method according to claim 1 wherein theheat-vulcanisable rubber is utilised as a plurality of strips extendingacross the surface of one of the elements.
 10. A method according toclaim 9 wherein at least two such strips are of different rubbers, eachdifferent rubber having the properties defined in claim
 1. 11. A methodaccording to claim 1 wherein the heat-vulcanisable rubber is utilised asa single sheet.
 12. A method according to claim 1 wherein theheat-vulcanisable rubber covers from 15 to 40% of the area of thesurface to which it is applied.
 13. A method according to claim 1wherein the heat-vulcanisable rubber is a natural, butyl or neoprenerubber.
 14. A METHOD OF ADHERING A HOT TOP LINING SLAB TO AN INNERSURFACE OF AN INGOT MOULD OR BOX, WHICH METHOD COMPRISES FIRST PRIMINGTHE REAR SURFACE OF THE LINING SLAB WITH A SOLUTION COMPRISING A RUBBERAND A TACKIFIER, THEN EXTRUDING A PLURALITY OF STRIPS OF AHEAT-VULCANISABLE RUBBER HAVING THE FOLLOWING PROPERTIES: A. A MOONEYVISCOSITY, AFTER 4 MINUTES AT 100*C OF 24-70 UNITS, B. A TORQUE AFTER 1MINUTE AT 160*C OF 1-30 INCH.LBS., C. A SCORCH TIME OF NOT GREATER THAN3 1/2 MINUTES, D. A VULCANISATION RATE OF 9-20% INCH.LBS. PER MINUTE, E.A TIME TO 100% CURE OF 10-30 MINUTES, AND F. A QUALITY LEVEL OF 50-90INCH.LBS. ONTO THE PRIMED SURFACE WHILE THE PRIMER IS STILL WET,ALLOWING THE ASSEMBLY TO CURE TO GIVE A RUBBER STRIP FIRMLY ADHERED TOTHE SRFACE, AND ADHERING THE RUBBER STRIP TO THE INNER SURFACE OF THEINGOT MOULD OR HEAD BOX WITH A TACKY PRESSURE SENSITIVE MATERIAL.
 15. Ahot top lining insulator slab assembly prepared by first priming therear surface of the lining slab with a solution comprising a rubber anda tackifier; then extruding a plurality of strips of a heat-vulcanisablerubber having the following properties: a. a Mooney viscosity, after 4minutes at 100*C of 24-70 units; b. a torque after 1 minute at 160*C of130 inch.lbs; c. a scorch time of not greater than 3 1/2 minutes; d. avulcanisation rate of 9-20 inch.lbs. per minute; e. a time to 100% cureof 10-30 minutes, and f. a quality level of 50-90 inch.lbs. onto theprimed surface while the primer is still wet; allowing the assembly tocure to give a rubber strip firmly adhered to the surface.
 16. A methodof adhering a plurality of elements, which comprises adhering togetheran insulator in the form of a hot top lining slab to an inner metalsurface of an ingot mould or a head box via a layer of aheat-vulcanisable rubber in the form of a plurality of strips extendingacross the surface of one of the elements, said rubber having thefollowing properties; a. a Mooney viscosity, after 4 minutes at 100*C of24-70 units; b. a torque after 1 minute at 160*C of 1-30 inch.lbs.; c. ascorch time of not greater than 3 1/2 minutes; d. a vulcanisation rateof 9-20 inch.lbs. per minute; e. a time to 100% cure of 10-30 minutes,and f. a quality level of 50-90 inch.lbs.